Code for Roman Numeral Kata post at http://fsharpforfunandprofit.com/posts/roman-numeral-kata/

RomanNumeralKata.fsx

System.IO.Directory.SetCurrentDirectory __SOURCE_DIRECTORY__

// The following DLLs were fetched using NuGet
#r @".\packages\FsCheck.0.9.2.0\lib\net40-Client\FsCheck.dll"
#r @".\packages\NUnit.2.6.3\lib\nunit.framework.dll"

open FsCheck
open NUnit.Framework

// ======================================
// Port of the ruby test code
// ======================================
module PortOfRubyCode =
    
    let arabicToRoman arabic = 
        "" // implementation to do

    [<Test>]
    let ``For certain inputs, expect certain outputs``() = 
        let testpairs = [ 
          (1,"I")
          (2,"II")
          (4,"IV")
          (5,"V")
          (9,"IX")
          (10,"X")
          // etc
          (900,"CM")
          (1000,"M")
          (3497,"MMMCDXCVII")
          ]
        for (arabic,expectedRoman) in testpairs do
           let roman = arabicToRoman arabic
           Assert.AreEqual(expectedRoman, roman)

// ======================================
// Testing all inputs
// ======================================
module TestingAllInputs =

    let arabicToRoman arabic = 
        "" // implementation to do

    let assertMaxRepetition str count input = 
        () // implementation to do

    [<Test>]
    let ``For all valid inputs, there must be a max of four "I"s in a row``() = 
        for i in [1..4000] do
           let roman = arabicToRoman i
           roman |> assertMaxRepetition "I" 4

    let assertSuffix suffix input = 
        () // implementation to do

    let assertNonSuffix suffix input = 
        () // implementation to do

    [<Test>]
    let ``For all valid inputs with two in the units, there must be exactly two "I"s at the end``() = 
        for i in [2..10..4000] do  // 2 to 4000 by steps of 10
           let roman = arabicToRoman i
           roman |> assertSuffix "II"
           roman |> assertNonSuffix "III"


// ======================================
// Property based testing example
// ======================================
module PropertyBasedTestingExample =

    let arabicToRoman arabic = 
        "" // implementation to do

    let assertMaxRepetition str count input = 
        () // implementation to do


    // Define a property that should be true for all inputs
    let ``has max rep of four Is`` arabic = 
       let roman = arabicToRoman arabic
       roman |> assertMaxRepetition "I" 4

    // Explicitly enumerate all inputs...
    [<Test>]
    let ``For all valid inputs, there must be a max of four "I"s``() = 
        for i in [1..4000] do
           //check that the property holds
           ``has max rep of four Is`` i

    // ...Or use FsCheck to generate inputs for you
    do
        let isInRange i = (i >= 1) && (i <= 4000)
        // input is in range implies has max of four Is
        let prop i = isInRange i ==> ``has max rep of four Is`` i
        // check all inputs for this property
        Check.Quick prop

 
    let assertMaxOccurs str max input = 
        () // implementation to do

    // Define a property that should be true for all inputs
    let ``if arabic has 4 tens then roman has one XL otherwise none`` arabic = 
       let roman = arabicToRoman arabic
       let has4Tens = (arabic % 100 / 10) = 4 
       if has4Tens then
           assertMaxOccurs "XL" 1 roman
       else 
           assertMaxOccurs "XL" 0 roman

    // Explicitly enumerate all inputs...
    [<Test>]
    let ``For all valid inputs, check the XL substitution``() = 
        for i in [1..4000] do
           ``if arabic has 4 tens then roman has one XL otherwise none`` i

    // ...Or again use FsCheck to generate inputs for you
    do
        let isInRange i = (i >= 1) && (i <= 4000)
        let prop i = isInRange i ==> ``if arabic has 4 tens then roman has one XL otherwise none`` i
        Check.Quick prop

// ======================================
// Complete property based testing using CustomAssert
// ======================================

module Test_Using_CustomAssert = 

    // the implementation to use is set later
    let mutable arabicToRoman' : int -> string  = 
        fun arabic -> failwith "Must be set for testing"

    // ======================================================
    // helper functions
    // ======================================================

    let inputRange() = [1..4000]

    let assertTrue(b,msg) = 
        if not b then printfn "FAIL: %s"  msg

    let assertMaxRepetition str count (input:string) = 
        let find = String.replicate (count+1) str 
        let b = input.Contains find |> not
        let msg = sprintf "assertMaxRepetition %s %i %s" str count input
        assertTrue(b,msg)

    let assertOccurs (str:string) count (input:string) = 
        // if it occurs once, then the string will be split into two, etc.
        let b = input.Split( [| str |],System.StringSplitOptions.None).Length = count + 1  
        let msg = sprintf "assertOccurs %s %i %s" str count input
        assertTrue(b,msg)

    let replace (oldVal,newVal) (s:string) =
        s.Replace(oldValue=oldVal,newValue=newVal)

    let removeAbbreviations (s:string) = 
        s 
        |> replace("IV","IIII")
        |> replace("IX","VIIII")
        |> replace("XL","XXXX")
        |> replace("XC","LXXXX")
        |> replace("CD","CCCC")
        |> replace("CM","DCCCC")

    let assertSortedHighToLow (s:string) = 
        let unsorted = 
            s
            |> removeAbbreviations 
            |> replace("I","1")
            |> replace("V","2")
            |> replace("X","3")
            |> replace("L","4")
            |> replace("C","5")
            |> replace("D","6")
            |> replace("M","7")
            |> List.ofSeq
        let sortedHighToLow = unsorted |> List.sort |> List.rev
        //assert they are the same
        let b = unsorted = sortedHighToLow
        let msg = sprintf "assertSortedHighToLow %s" s
        assertTrue(b,msg)

    // ======================================================
    // Properties
    // ======================================================
    let maxRepetitionProperty str count = 
        inputRange() |> List.iter (fun arabic -> 
            let roman = arabicToRoman' arabic
            roman |> assertMaxRepetition str count 
            )
        printfn "Completed maxRepetitionProperty %s %i" str count 

    let foursProperty place str = 
        inputRange() |> List.iter (fun arabic -> 
            let roman = arabicToRoman' arabic
            let has4s = (arabic % (place*10) / place) = 4 
            if has4s then
                assertOccurs str 1 roman
            else 
                assertOccurs str 0 roman
            )
        printfn "Completed foursProperty %i %s" place str 

    let ninesProperty place str = 
        inputRange() |> List.iter (fun arabic -> 
            let roman = arabicToRoman' arabic
            let has9s = (arabic % (place*10) / place) = 9
            if has9s then
                assertOccurs str 1 roman
            else 
                assertOccurs str 0 roman
            )
        printfn "Completed ninesProperty %i %s" place str 

    let ``has max rep of three Is``() = 
        maxRepetitionProperty "I" 3

    let ``has max rep of one V``() = 
        maxRepetitionProperty "V" 1

    let ``has max rep of three Xs``() = 
        maxRepetitionProperty "X" 3

    let ``has max rep of one L``() = 
        maxRepetitionProperty "L" 1

    let ``has max rep of three Cs``() = 
        maxRepetitionProperty "C" 3

    let ``has max rep of one D``() = 
        maxRepetitionProperty "D" 1

    let ``has max rep of four Ms``() = 
        maxRepetitionProperty "M" 4

    let ``if arabic has 4 ones then roman has one IV otherwise none``() = 
        foursProperty 1 "IV" 

    let ``if arabic has 9 ones then roman has one IX otherwise none``() = 
        ninesProperty 1 "IX" 

    let ``if arabic has 4 tens then roman has one XL otherwise none``() = 
        foursProperty 10 "XL" 

    let ``if arabic has 9 tens then roman has one XC otherwise none``() = 
        ninesProperty 10 "XC" 

    let ``if arabic has 4 hundreds then roman has one CD otherwise none``() = 
        foursProperty 100 "CD" 

    let ``if arabic has 9 hundreds then roman has one CM otherwise none``() = 
        ninesProperty 100 "CM" 

    let ``is sorted from M to I``() = 
        inputRange() |> List.iter (fun arabic -> 
            let roman = arabicToRoman' arabic
            roman |> assertSortedHighToLow
            )
        printfn "Completed is sorted from M to I"

    let checkAllProperties() = 
        ``has max rep of three Is``()
        ``has max rep of one V``()  
        ``has max rep of three Xs``()  
        ``has max rep of one L``()  
        ``has max rep of three Cs``()  
        ``has max rep of one D``()  
        ``has max rep of four Ms``()  
        ``if arabic has 4 ones then roman has one IV otherwise none``()  
        ``if arabic has 9 ones then roman has one IX otherwise none``()  
        ``if arabic has 4 tens then roman has one XL otherwise none``()  
        ``if arabic has 9 tens then roman has one XC otherwise none``()  
        ``if arabic has 4 hundreds then roman has one CD otherwise none``()  
        ``if arabic has 9 hundreds then roman has one CM otherwise none``()  
        ``is sorted from M to I``()  
            
// ======================================
// Complete property based testing using FsCheck
// ======================================

module Test_Using_FsCheck = 

    // the implementation to use is set later
    let mutable arabicToRoman' : int -> string  = 
        fun arabic -> failwith "Must be set for testing"

    // ======================================================
    // helper functions
    // ======================================================

    let inputRange = Gen.choose(1,4000) |> Arb.fromGen

    let assertMaxRepetition str count (input:string) = 
        let find = String.replicate (count+1) str 
        input.Contains find |> not

    let assertOccurs (str:string) count (input:string) = 
        // if it occurs once, then the string will be split into two, etc.
        input.Split( [| str |],System.StringSplitOptions.None).Length = count + 1  

    let replace (oldVal,newVal) (s:string) =
        s.Replace(oldValue=oldVal,newValue=newVal)

    let removeAbbreviations (s:string) = 
        s 
        |> replace("IV","IIII")
        |> replace("IX","VIIII")
        |> replace("XL","XXXX")
        |> replace("XC","LXXXX")
        |> replace("CD","CCCC")
        |> replace("CM","DCCCC")

    let assertSortedHighToLow (s:string) = 
        let unsorted = 
            s
            |> removeAbbreviations 
            |> replace("I","1")
            |> replace("V","2")
            |> replace("X","3")
            |> replace("L","4")
            |> replace("C","5")
            |> replace("D","6")
            |> replace("M","7")
            |> List.ofSeq
        let sortedHighToLow = unsorted |> List.sort |> List.rev
        //assert they are the same
        unsorted = sortedHighToLow

    // ======================================================
    // Properties
    // ======================================================
    type ImplementationProperties() = 

        static let maxRepetitionProperty str count = 
            Prop.forAll inputRange (fun arabic -> 
                let roman = arabicToRoman' arabic
                roman |> assertMaxRepetition str count 
                )

        static let foursProperty place str = 
            Prop.forAll inputRange (fun arabic -> 
                let roman = arabicToRoman' arabic
                let has4s = (arabic % (place*10) / place) = 4 
                if has4s then
                    assertOccurs str 1 roman
                else 
                    assertOccurs str 0 roman
                )

        static let ninesProperty place str = 
            Prop.forAll inputRange (fun arabic -> 
                let roman = arabicToRoman' arabic
                let has9s = (arabic % (place*10) / place) = 9
                if has9s then
                    assertOccurs str 1 roman
                else 
                    assertOccurs str 0 roman
                )

        static member ``has max rep of three Is`` = 
            maxRepetitionProperty "I" 3

        static member ``has max rep of one V`` = 
            maxRepetitionProperty "V" 1

        static member ``has max rep of three Xs`` = 
            maxRepetitionProperty "X" 3

        static member ``has max rep of one L`` = 
            maxRepetitionProperty "L" 1

        static member ``has max rep of three Cs`` = 
            maxRepetitionProperty "C" 3

        static member ``has max rep of one D`` = 
            maxRepetitionProperty "D" 1

        static member ``has max rep of four Ms`` = 
            maxRepetitionProperty "M" 4

        static member ``if arabic has 4 ones then roman has one IV otherwise none`` = 
           foursProperty 1 "IV" 

        static member ``if arabic has 9 ones then roman has one IX otherwise none`` = 
           ninesProperty 1 "IX" 

        static member ``if arabic has 4 tens then roman has one XL otherwise none`` = 
           foursProperty 10 "XL" 

        static member ``if arabic has 9 tens then roman has one XC otherwise none`` = 
           ninesProperty 10 "XC" 

        static member ``if arabic has 4 hundreds then roman has one CD otherwise none`` = 
           foursProperty 100 "CD" 

        static member ``if arabic has 9 hundreds then roman has one CM otherwise none`` = 
           ninesProperty 100 "CM" 

        static member ``is sorted from M to I`` = 
            Prop.forAll inputRange (fun arabic -> 
                let roman = arabicToRoman' arabic
                roman |> assertSortedHighToLow
                )

        
// ======================================
// Tally-based implementation -- version 1
// ======================================

module TallyImplementation_V1 = 

    let arabicToRoman arabic = 
       String.replicate arabic "I"


module TallyImplementation_V1_Demo = 
    open TallyImplementation_V1

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IIII"
    testArabicToRoman 5    // "IIIII"
    testArabicToRoman 6    // "IIIIII"
    testArabicToRoman 10   // "IIIIIIIIII" 
    testArabicToRoman 12   // "IIIIIIIIIIII" 
    testArabicToRoman 16   // "IIIIIIIIIIIIIIII" 
    testArabicToRoman 40   // "IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII" 
  
// ======================================
// Tally-based implementation -- version 2
// ======================================

module TallyImplementation_V2 = 

  let arabicToRoman arabic = 
    (String.replicate arabic "I")
     .Replace("IIIII","V")

module TallyImplementation_V2_Demo = 
    open TallyImplementation_V2

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IIII"
    testArabicToRoman 5    // "V"
    testArabicToRoman 6    // "VI"
    testArabicToRoman 10   // "VV" 
    testArabicToRoman 12   // "VVII" 
    testArabicToRoman 16   // "VVVI" 
    testArabicToRoman 40   // "VVVVVVVV" 

// ======================================
// Tally-based implementation -- version 3
// ======================================  

module TallyImplementation_V3 = 

  let arabicToRoman arabic = 
    (String.replicate arabic "I")
     .Replace("IIIII","V")
     .Replace("VV","X")

module TallyImplementation_V3_Demo = 
    open TallyImplementation_V3

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IIII"
    testArabicToRoman 5    // "V"
    testArabicToRoman 6    // "VI"
    testArabicToRoman 10   // "X" 
    testArabicToRoman 12   // "XII" 
    testArabicToRoman 16   // "XVI" 
    testArabicToRoman 40   // "XXXX" 

// ======================================
// Tally-based implementation -- V4
// ======================================

module TallyImplementation_V4 = 

    let arabicToRoman arabic = 
       (String.replicate arabic "I")
        .Replace("IIIII","V")
        .Replace("VV","X")
        .Replace("XXXXX","L")
        .Replace("LL","C")
        .Replace("CCCCC","D")
        .Replace("DD","M")
        // optional substitutions
        .Replace("IIII","IV")
        .Replace("VIV","IX")
        .Replace("XXXX","XL")
        .Replace("LXL","XC")
        .Replace("CCCC","CD")
        .Replace("DCD","CM")
    
module TallyImplementation_V4_Demo = 
    open TallyImplementation_V4

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IV"
    testArabicToRoman 5    // "V"
    testArabicToRoman 6    // "VI"
    testArabicToRoman 10   // "X" 
    testArabicToRoman 12   // "XII" 
    testArabicToRoman 16   // "XVI" 
    testArabicToRoman 40   // "XL" 
    testArabicToRoman 946  // "CMXLVI" 
    testArabicToRoman 3497 // "MMMCDXCVII" 

    
// ======================================
// Tally-based implementation -- complete with property based tests
// ======================================

module TallyImplementation_Complete = 

    let arabicToRoman' arabic = 
       (String.replicate arabic "I")
        .Replace("IIIII","V")
        .Replace("VV","X")
        .Replace("XXXXX","L")
        .Replace("LL","C")
        .Replace("CCCCC","D")
        .Replace("DD","M")
        // optional substitutions
        .Replace("IIII","IV")
        .Replace("VIV","IX")
        .Replace("XXXX","XL")
        .Replace("LXL","XC")
        .Replace("CCCC","CD")
        .Replace("DCD","CM")

    let arabicToRoman arabic = 
       if arabic < 0 then None
       else if arabic > 4000 then None
       else if arabic = 0 then Some ""
       else Some (arabicToRoman' arabic)

module TallyImplementation_Complete_Demo = 
    open TallyImplementation_Complete

    let testArabicToRoman i =
       printfn "%i ==> %A" i (arabicToRoman i)

    testArabicToRoman -1   // None
    testArabicToRoman 0    // Some ""
    testArabicToRoman 1    // Some "I"
    testArabicToRoman 4    // Some "IV"
    testArabicToRoman 5    // Some "V"
    testArabicToRoman 6    // Some "VI"
    testArabicToRoman 10   // Some "X" 
    testArabicToRoman 12   // Some "XII" 
    testArabicToRoman 16   // Some "XVI" 
    testArabicToRoman 40   // Some "XL" 
    testArabicToRoman 946  // Some "CMXLVI" 
    testArabicToRoman 3497 // Some "MMMCDXCVII" 
    testArabicToRoman 10000 // None


module TallyImplementation_Complete_Test_Using_CustomAssert = 

    // set the implementation to use
    Test_Using_CustomAssert.arabicToRoman' <- TallyImplementation_Complete.arabicToRoman'

    // check all the properties
    Test_Using_CustomAssert.checkAllProperties()

    
module TallyImplementation_Complete_Test_Using_FsCheck = 

    // set the implementation to use
    Test_Using_FsCheck.arabicToRoman' <- TallyImplementation_Complete.arabicToRoman'

    // check all the properties
    Check.All<Test_Using_FsCheck.ImplementationProperties>({Config.Quick with MaxTest = 4000})


// ======================================
// place-based implementation without abbreviations
// ======================================

module PlaceBasedImplementation_WithoutAbbreviation = 

    let biQuinaryDigits place (unit,five) arabic =
        let digit =  arabic % (10*place) / place
        match digit with
        | 0 -> ""
        | 1 -> unit
        | 2 -> unit + unit
        | 3 -> unit + unit + unit
        | 4 -> unit + unit + unit + unit
        | 5 -> five
        | 6 -> five + unit
        | 7 -> five + unit + unit
        | 8 -> five + unit + unit + unit
        | 9 -> five + unit + unit + unit + unit
        | _ -> failwith "Expected 0-9 only"

    let arabicToRoman' arabic = 
        let units = biQuinaryDigits 1 ("I","V") arabic
        let tens = biQuinaryDigits 10 ("X","L") arabic
        let hundreds = biQuinaryDigits 100 ("C","D") arabic
        let thousands = biQuinaryDigits 1000 ("M","?") arabic
        thousands + hundreds + tens + units

    let arabicToRoman arabic = 
        if arabic < 0 then None
        else if arabic > 4000 then None
        else if arabic = 0 then Some ""
        else Some (arabicToRoman' arabic)

module PlaceBasedImplementation_WithoutAbbreviation_Demo = 
    open PlaceBasedImplementation_WithoutAbbreviation

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman' i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IIII"
    testArabicToRoman 5    // "V"
    testArabicToRoman 6    // "VI"
    testArabicToRoman 10   // "X" 
    testArabicToRoman 12   // "XII" 
    testArabicToRoman 16   // "XVI" 
    testArabicToRoman 40   // "XXXX" 
    testArabicToRoman 946  // "DCCCCXXXXVI" 
    testArabicToRoman 3497 // "MMMCCCCLXXXXVII" 


// ======================================
// place-based implementation
// ======================================

module PlaceBasedImplementation = 

    let biQuinaryDigits place (unit,five,ten) arabic =
        let digit =  arabic % (10*place) / place
        match digit with
        | 0 -> ""
        | 1 -> unit
        | 2 -> unit + unit
        | 3 -> unit + unit + unit
        | 4 -> unit + five // changed to be one less than five
        | 5 -> five
        | 6 -> five + unit
        | 7 -> five + unit + unit
        | 8 -> five + unit + unit + unit
        | 9 -> unit + ten // changed to be one less than ten
        | _ -> failwith "Expected 0-9 only"

    let arabicToRoman' arabic = 
        let units = biQuinaryDigits 1 ("I","V","X") arabic
        let tens = biQuinaryDigits 10 ("X","L","C") arabic
        let hundreds = biQuinaryDigits 100 ("C","D","M") arabic
        let thousands = biQuinaryDigits 1000 ("M","?","?") arabic
        thousands + hundreds + tens + units

    let arabicToRoman arabic = 
        if arabic < 0 then None
        else if arabic > 4000 then None
        else if arabic = 0 then Some ""
        else Some (arabicToRoman' arabic)

module PlaceBasedImplementation_Demo = 
    open PlaceBasedImplementation

    let testArabicToRoman i =
       printfn "%i ==> %s" i (arabicToRoman' i)

    testArabicToRoman 1  // "I"
    testArabicToRoman 4    // "IV"
    testArabicToRoman 5    // "V"
    testArabicToRoman 6    // "VI"
    testArabicToRoman 10   // "X" 
    testArabicToRoman 12   // "XII" 
    testArabicToRoman 16   // "XVI" 
    testArabicToRoman 40   // "XL" 
    testArabicToRoman 946  // "CMXLVI" 
    testArabicToRoman 3497 // "MMMCDXCVII" 
    testArabicToRoman 4000 // "M?" 

module PlaceBasedImplementation_Test_Using_CustomAssert = 

    // set the implementation to use
    Test_Using_CustomAssert.arabicToRoman' <- PlaceBasedImplementation.arabicToRoman'

    // check all the properties
    Test_Using_CustomAssert.checkAllProperties()

    // Note that some of the tests fail when the input is 4000. 
    // This is because the output is "M?" rather than "MMMM"

module PlaceBasedImplementation_Test_Using_FsCheck = 

    // set the implementation to use
    Test_Using_FsCheck.arabicToRoman' <- PlaceBasedImplementation.arabicToRoman'

    // check all the properties
    Check.All<Test_Using_FsCheck.ImplementationProperties>({Config.Quick with MaxTest = 4000})

    // Note that some of the tests fail when the input is 4000. 
    // This is because the output is "M?" rather than "MMMM"

That's a lot of code for such a small application :)

That's a lot of code for such a small application :)